Wheel cooling

ABSTRACT

IN THE COOLING OF A STEEL RAILWAY WHEEL HAVING RELATIVELY THICK HUB AND TREAD PORTIONS AND A RELATIVELY THIN PLATE PORTION, IT IS IMPORTANT THAT UNDUE STRESSES ARE NOT SET UP IN THE PLATE PORTION, AND SIMULTANEOUSLY, THAT THE TREAD HARDNESS FOR GOOD WEAR QUALITIES WHILE THE HUB REMAINS SOFT FOR EASY MACHINABILITY. THIS PROBLEM IS SOLVED BY AIR COOLING THE WHEELS, THE HUBS OF WHICH HAVE BEEN COVERED BY AN INSULATING MATERIAL, UNITL THE HUBS ARE AT A TEMPERATURE BELOW THE CRITICAL TRANSFORMATION TEMPERATURES WHICH IS APPROXIMATELY 123*F.

Jan. 26, 1971 B. J, ECK 3,558,367

WHEEL COOLING Filed vom. 18 19s? INVENTOR,

BERNARD J.ECL,

WWW

ATT'YS United States Patent 3,558,367 WHEEL COOLING Bernard John Eck,Elmhurst, Ill., assignor to AMSTED Industries Incorporated, Chicago,III., a corporation of Delaware Filed Oct. 18, 1967, Ser. No. 676,274Int. Cl. C21d 1 70, 9/34 US. Cl. 148-3 3 Claims ABSTRACT OF THEDISCLOSURE In the cooling of a steel railway wheel having relativelythick hub and tread portions and a relatively thin plate portion, it isimportant that undue stresses are not set up in the plate portion, andsimultaneously, that the tread hardens for good wear qualities while thehub remains soft for easy machinability. This problem is solved by aircooling the wheels, the hubs of which have been covered by an insulatingmaterial, until the hubs are at a temperature below the criticaltransformation temperature which is approximately 1230 F.

It has been customary in prior art wheel cooling arrangements to removethe cast steel whels from the molds, cool them slowly in a cooling ovento a range of about 1150-1200 F., torch cut the axle hole, heat thewheels in a normalizing furnace to approximately 1700 F., and then coolthe wheels to approximately 1150 F., after which the hubs were forcecooled by water sprays or air jets in order to obtain proper stresspatterns in the plate portion of the wheels. The disadvantage of thisprocedure is that, while satisfactory stress patterns are obtained, thehub is of such hardness that it has very poor machinability.

If the entire wheels are air cooled other problems arise because the huband tread are at approxiamtely the same hardness. If, for example, therate of air cooling is such as to produce a tread with good wearqualities, the hub is difficult to machine. If, on the other hand, therate of air cooling is such as to produce a machinable hub, the tread istoo soft to provide wear qualities.

In the present arrangement a cast steel railway car Wheel is producedwhich has a tread sufliciently hard so as to have good wear propertieswhile the hub is soft enough to be easily machined.

The proposed method of cooling wheels will be better understood 'withreference to the single figure of the drawing which is a cross-sectionalview of a railway car wheel positioned on a cooling conveyor.

Referring to the drawing, the wheel 10 has a central relatively thickhub 12 and a relatively thick tread 14 interconnected by a relativelythin plate 16. The wheel is illustrated at that portion of themanufacturing cycle wherein an axle hole 17 has been torch cut and thewheel is being transported on a conveyor indicated schematically at 18.

In the preferred method of treating a cast steel railway car wheel, thewheels are moved from the mold and cooled to a temperature in the rangeof ll00 F. to 1200 F., after which an axle hole is torch cut through thewheel hub. The wheel is then heated in a normalizing furance to atemperature of approximately 1700 F. As each wheel emerges from thenormalizing furnace, it is placed upon an insulating disk 20 which ispositioned on slat conveyor 18. The insulating disk is preferably ofrefractory fiber glass construction but may be any ceramic insulatingmaterial which will withstand temperatures of up to 1700 F., or afibrous insulating material such as asbestos. A second insulating disk22 is placed on the upper face of the wheel hub. To provide ease ofhandling and to lend support to the fibrous insulating material, theindividual disks 20 and 22 may be supported by metallic plates 2.4though this is not essential. The wheels are permitted to cool in air,with the wheel treads completely exposed but with the wheel hubsinsulated so that the loss of heat from the hubs is retarded. Cooling inthis manner is continued until the hub temperature is below thetransformation temperature of the steel of which the wheel is cast. Thistransformation temperature will generally be approximately 1230 F. and,in practice, the wheels are cooled to a temperature within the range ofapproximately 0 F. to 1200 F. The foregoing method results in wheelshaving a preferred tread hardness in the range of approximately 265-300B.H.N., and the hub hardness less than about 340 B.H.N.

An alternate method, not quite as effective as the preferred methoddescribed above, is to provide a conveyor having a continuous strip ofinsulating material suspended thereabove and having a widthapproximately equal to the hub diameter. The wheels are then slowlycarried on the conveyor so that the hubs are always positionedimmediately below the strip of insulating material. In this arrangementthe wheel hubs are once again cooled at a slower rate than the wheelrims and the desired hardness characteristics are obtained. If desired,heating means in the form of a heating element, an induction coil or gasflames may be utilized in the strip to aid in retarding loss of heatfrom the Wheel hubs.

I claim:

1. A method of making a steel railway wheel, comprising the steps offorming steel while molten to the shape of a wheel, then cooling thewheel to a temperature value within the range of about 1200 F. to roomtemperature, then heating the wheel in a furnace to a normalizingtemperature of about 1700" F., and as the wheel emerges from the furanceplacing a non-metallic insulating disk upon each face of the wheel hub,then cooling the wheel in air until the hub portion has cooled to atemperature of at least about 1200 F.

2. The method of claim 1 wherein the insulating disk comprisesrefractory glass fibers.

3. The method of claim 1 and including the step of first providing eachinsulating disk with a metallic support.

References Cited UNITED STATES PATENTS 1,071,012 8/1913 Unger 14-1461,859,623 5/1932 Gregg l48l49 2,029,819 2/19'36 Gregg et a1. 148l49X3,043,317 7/1962 Hursen 266-6 3,370,993 2/1968 Carpenter et al. 14813.1

CHARLES N. LOVEDL, Primary Examiner US. Cl. X.R. 148-146, 149

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3558367Dated January 26, 1971 Inventor(s) Bernard John Eek It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 2, line 22 change "340B.H .N. to --240 B.H.N.

Signed and sealed this 29th day of February 1972.

(SEAL) Attest ROBERT GOTTSCHALK ELWARD ILFLETCHER, JR.

Commissioner of Patents Attesting Officer

